The invention relates to a method, and an assembly for practicing the method, for removing endodontic instrument fragments or the like from root canals. As is well known, the endodontic treatment conventionally contemplates appropriate dressing of the access cavity to the root-pulp channel with removal of pulp in the cavity; location of the opening of the radicular channels and measuring the depth thereof; removal of radicular contents and organic waste to the apex with cleansing by introducing suitable chemical solutions; and channel drying and tridimensional filling thereof. During practice of the endodontic treatment, foreign objects are often located or left in the root canal, such as fragments of root canal instruments (such as barbed broaches, reamers, files and rotary burs), obturating material such as silver cones and gutta percha; condenser points, lentulo spirals, pins and posts. While solvents can penetrate root canals obstructed by some foreign objects, and silver points can be removed with conventional instruments, some foreign objects--such as fragments of endodontic instruments--are difficult to remove with conventional root canal pliers, silver point retrievers, or other conventional structures. Difficulties especially ensue where an instrument breaks before completion of the bio-mechanical preparation of the canal since in such circumstances enlightened technique requires removal of the fragment before filling.
In addition to the use of solvents, silver point retrievers, and root canal pliers, prior art techniques for foreign object removal have included the introduction of a broach wrapped in cotton into the canal in the hopes that the fragment will become enmeshed in the cotton. Other proposals include the use of splinter forceps, rasps with sharp cutting edges, and the use of trepan burs to remove the tooth structure around the fragment so that an extractor can be introduced to grasp the end of the fragment to remove it. While such techniques are often successful, they may require the removal of some essential root structure, are time consuming, are difficult to utilize in anything besides straight canals, and require relatively expensive equipment.
According to the method and apparatus of the present invention, the extraction of endodontic instrument fragments or the like is substantially simplified, a method being provided that has broad applicability, is useful both in straight and curved canals, is not particularly time consuming, does not require the removal of essential root structure, and employs very inexpensive components.
The method according to the present invention utilizes a wire and an elongated tube. The wire is formed into a loop and a free end of the wire is passed through the tube so that the loop extends from one side of the tube and the free end extends from the opposite side of the tube. The loop and a portion of the tube are inserted into the root canal alongside the fragment, in a clear area between the fragment and the canal wall. The loop is slid past the fragment so that the closed portion of the loop is on the opposite side of the fragment than the tube, a force is exerted on the wire free end sufficient to cause the loop and tube to tightly hold the fragment, and the tube and loop--with tightly held fragment--are withdrawn from the root canal. If it is necessary to form the clearance alongside the fragment, the clearance formation can be accomplished without the removal of essential tooth structure since only a small portion of the tooth structure or other material alongside the fragment need be removed. Preferably both free ends of the wire pass through the tube, and are gripped at the ends thereof opposite the loop by a mosquito hemostat or the like, which is rotated about an axis perpendicular to the direction of elongation of the tube to effect tightening of the wire on the fragment.
The loop is set for introduction into the root canal by placing an object in the loop having a larger cross-sectional area than that of the fragment; placing the object at about a 45.degree. angle with respect to the tube; exerting a force on the wire free end sufficient to cause tightening of the loop around the object; and removing the object from the loop. The elongated tube may be formed from a disposable dental injector needle having a hub with the hollow needle extending through the hub on both sides thereof with a bevel cut on the most distal end of the needle. The needle is cut off just before the bevel cut and so that it is substantially flush with the hub on the end thereof opposite the bevel cut.
The retrieving assembly according to the present invention is very inexpensive, comprising a wire, an elongated tube having a cross-sectional area greater than the cross-sectional area of the wire, and a clamping means (such as a mosquito hemostat) for securely clamping the wire ends for effecting movement of the wire with respect to the tube. Preferably an elongated hub is formed at one end of the tube, and the tube is flexible.
It is the primary object of the present invention to provide a versatile, simple, inexpensive method and assembly for retrieving foreign objects from root canals. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.